S
M
T
W
T
F
S
30
81°
61°
31
79°
61°
1
78°
67°
2
78°
68°
3
85°
67°
4
86°
68°
5
85°
65°
6
81°
60°
7
80°
62°
8
80°
59°
9
78°
58°
10
77°
58°
11
76°
59°
12
79°
58°
13
78°
63°
14
82°
63°
15
77°
57°
16
76°
60°
17
75°
59°
18
76°
62°
19
77°
54°
20
77°
57°
21
75°
55°
22
79°
54°
23
74°
53°
24
73°
53°
25
73°
57°
26
74°
57°
27
75°
59°
28
77°
59°
29
77°
51°
30
71°
54°
1
70°
59°
2
76°
57°
3
76°
50°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
September Weather in New Castle
New Castle's September 2026 forecast shows daily high temperatures ranging from 70° to 86°, with overnight lows between 50° and 68°. The average high for September is 77° with an average low of 59°. AccuWeather's monthly forecast extends further ahead than any other source, with day-by-day RealFeel® Temperatures giving a complete picture of how September weather will actually feel in New Castle. See also: October | November | December.
